This invention relates to a machine and method for manufacturing button connectors which are in the form of a wad of crumpled wire. This type of button connector is also called the "fuzz button".
The button connector produced in this invention uses fine, springy, highly conductive wire to make minuscule connectors that are pressed into holes in insulating boards. This wire material has been around for many years and is essentially the same as the finely woven wire mesh used to control electromagnetic interference in highly sensitive radio frequency equipment.
It is widely known that a large amount of electronic system malfunctions are caused by failures at interconnection points. Solder joints are highly vulnerable to temperature cycling and to vibration and shock. Multiprong chips and board-edge connectors (which contain many solder joints) are also vulnerable to mechanical wear and breakage.
The button connector is a substantially cylindrical wad of wire, approximately 0.050" in diameter and the same in overall length. It protrudes approximately 0.005" to 0.010" at each end so that when compressed, its springiness keeps it in place and establishes excellent contact at both ends.
By controlling the length of wire that is wadded into each button connector (and, of course, the thickness of the board and size of the holes), button density and therefore transmissivity and the resultant compression force can be precisely specified and maintained within close tolerances. At the same time, over-compression, accidental bending, high-insertion forces, wearout, and breakage--problems that plague conventional prong and finger connectors--are completely eliminated.
The machine of this invention incorporates actuating means, such as motors and air cylinders, which respond to actuate a plurality of independent means to rotate, revolve, spin or translate. The machine comprises a wire supply means for supplying the wire to be knurled by a knurling means. The knurled wire is then guided to wrap a specified number of turns around first and second protruding needles. The wrapped wire is again spun with reference to a longitudinal axis thereof, with the second protruding needle fixed, to form a substantially helical shape.